Mount Rainier is a city in Prince George's County, Maryland, United States. The population was 8,080 at the 2010 census. Bordering Washington, D.C., Mount Rainier got its start as a streetcar suburb. According to local tradition, surveyors from the Pacific Northwest named the town, giving the streets names such as "Shasta" and "Cascade". Historic U.S. 1 runs through the center of the town and serves as the main street and central business district.Bordering areas Brentwood (to the east) Cottage City (to the southeast) Colmar Manor (to the southeast) Hyattsville (to the northeast) Washington, D.C. (to the southwest)GeographyMount Rainier is located at .According to the United States Census Bureau, the city has a total area of 0.65sqmi, all of it land.DemographicsMount Rainier has attracted a significant gay and lesbian population. In 2000, same-sex couples accounted for 1.0 percent of households, almost double the national average.